All posts by Simon

Recipe: German Küchle

One of the traditional baked goods in the Southern part of Germany: so-called Kuechle.

Recipe:
500 g wheat flour, 50 g sugar, 60 g butter, 2 eggs, 220-250 mL milk, small quantity of salt, yeast.

Prepare a yeast dough, knead it thoroughly, let it rise, knead again, and finally form small round pieces, about 15 pieces. Let rise again for 15 minutes.

For baking, heat oil (better: clarified butter) to 175-185 degrees C (ideally, use a thermometer). Then, with fingers covered with some oil or butter, pull the kuechle into shape and bake floating on the oil, turn around once the color of the 1st side is right, bake the 2nd side, then take out and put on some kitchen paper to soak-off the residual oil. Cover with some powdered sugar. Eat fresh, or freeze.

HP 8659B Spectrum Analyzer: mostly, the known issues

Mostly, the well-known issues for this 8569B: a bad fan, a bad 5.2 V supply capacitor (see the 5.2 V rail ripple below!), some issues with the display adjustment, and a bad control assembly with contact broken off. The control assembly, interestingly enough, somebody else had fixed some part of it before, from the handwriting, an American.
Still some minor issues with the Z axis control (brightness control), but this will be fixed soon, and then the analyzer will be thoroughly tested and will find good use again.

Harvest Highlights 2018: Two-continent gardening

Believe me, it is a challenge to have two gardens, one in Germany (allotment 44), one in Japan (behind the house), but after all, some good harvest results this year.

A good year for peaches in Ludwigshafen, Germany!

Many jars of jam of German blackberries, and other kinds of berries…

Japanese experiments – starting with radish, tomato, cabbage, beans, and EDAMAME (soy beans that are harvested green).

Edamame harvest… great with some beer!

Boil for 5 minutes in salt water, then cool down quickly with cold water and eat slightly cooled (don’t eat the shells!).

Pizza and Baguette Oven: From China, to Japan

One project for my new Japanese residence – a deck oven, to prepare pizza, baguette, and other baked goods, not only for myself, but also for friends, colleagues, etc.

Surprisingly, ovens, even regular household ovens, are virtually unknown in Japan. All is centered around microwaves and rice cookers, or fish grills, but nobody seems to need anything more than a small toaster oven. Well, for me, a well-working oven is absolutely essential for survival, to bake bread, pizza, and lasagne.

A deck oven, in contrast to a convection oven, transfers heat by contact and radiation more then by moving hot air around. There is a lot of science behind this, but we can leave the detail explanation to baking experts, anyway, if you want to bake a good baguette, bread, or pizza, you need a deck oven (which can have metal or stone floor – this one has metal, which is quite good for fast heat up and easy cleaning).

How to get a deck oven in Japan – it’s not easy, unless you want to pay thousands of dollars for a top brand professional imported German deck oven, or some high end Japanese equipment. Fortunately, China is close-by, and after some weeks of waiting, customs formality (You really want to import food processing equipment for use in Japan??? How come???), the big box arrived, about 100 kgs of metal and insulation. It is well build, some small shipment damage, but nothing that can’t be fixed, and it is recommended to inspect such equipment anyway, before you use it. It is from the Honglian company. YXY-10 gas deck oven, which can fit one large tray 50×60 cm easily, or three pizzas.
It has full electronic control of the heaters, digital display, high voltage pulse ignition, separate regulation of bottom and top temperature. All heavy duty. You can use steel or aluminum trays, or bake directly on a pizza mesh on the floor of the oven.

A lot of parts for little money!

Clean out the dirt and residues from manufacturing before using it. Anyway, it is a good idea to run it for a while at high temperature to get rid of all the oils and chemical residues.

Still some more work to do before firing up, electric supply installed (oven designed for 220 Volts – I also want to operate it in Germany later, but Japan has 100 Volts only), but the gas supply system (LPG) still needs some work, stay tuned!

Moving to Japan: Busy times…

Recently, not so much activity in the workshop, for a simple reason – I was moving to Japan. Still keeping the German main workshop, it is only a temporary work assignment, but temporary can mean two or three years in this case. Anyway, Japan is a great place and this move is to the real Japan, Ube, Yamaguchi, not some expat community in a big international city.

With the help for kind colleagues and the big enterprise, all has been set up in the meantime and life is carrying on along the usual path…

The Japanese house, it is of traditional style, which means, it is hot in summer and cold in winter, but at least you get a better connection to nature, and it is a very healthy life to have fresh air and wind moving trough the big open windows rather than to sit in a hermetically close skyscraper.

Not to miss, the Japanese garden!

… Vegetable garden …

The temporary workshop – I can’t go to such far away places without at least a phase noise measurement test set.

My latest acquisition, an electro-mechanical device called “Toyota Aqua”, aka Prius C – very good fuel efficiency, thanks to its hybrid drive train. Sorry, no service manual for this one but it’s great to explore the beauty of Yamaguchi Prefecture.

Meridian 506 CD Player: a hot driver

This report is about a really high-end (made in UK) compact disc player – a Meridian 506.
It had some issues with the drive circuit, with the TDA2030 running hot, and sometimes not reacting to the front panel control.

The drive mechanics, it is a quite simple setup – a DC motor with pulley arrangement, and rubber ring.

The cooling plate – just a small piece of metal. Running all good when when the CD compartment is opened and closed quickly, but there will be issues if for some reason the CD deck is not closing quickly – motor switch-off is controlled by the end switches.

The main driver is TDA2030, and an additional issue is the closeness of the heatsink to the metal case. Just some Kapton tape, which had some damage already. Maybe making contact at times (tab is connected to Pin 3, VS-).

Added a big heatsink the TDA2030, which is now also well-insulated from the case.

All working fine again!

The TDA2030 – it’s not a motor driver, but an audio amplifier by design. But essentially, it is a high power opamp, so it can be handy to control motors, coils, etc.

I also made use of the opportunity, please see the zip file.

meridian cd player 506 firmware

You can also find a collection of Meridian schematics in the manuals’ archive: Meridian Schematics, please request the password by email if you need access.

Auna AV2-CD508 HiFi Amplifier: start-up power supply repair

The Auna AV2-CD508 is a quite nice and affordable amplifier, the case is pretty solid, aluminum front, steel case, and the controls are all easy to operate.

It’s a “600 W” peak amplifier, but won’t take more than 80 Watts, so it is more likely a 2x 40 W amplifier – still, 40 Watts are a lot of sound power.

Unfortunately, this set reached my workshop for repair, symptom: it doesn’t switch on, no signs of any activity. After some measurements, the fault is found it the auxiliary 5 V power supply, this is always on, to power-up the main power supply and the rest of the circuit. The auxiliary supply is controlled by a SF5922S switchmode controller, SO-8. Unfortunately, this part is only available in China, and doesn’t seem to last anyway, so I removed the power supply control, and added some wires to an external supply.

… the external supply, a 5 V power supply. Also used it to measure the current. Turns out, the auxiliary supply only needs to provide some 100 mA of current, not a lot.

With the lab supply connected, and the Auna plugged in, it powers up OK and all working!!

That’s the amplifier board, solder side. The auxiliary pwr supply controller marked in red.

With such a device, better not lose too much time, and I decided to add a completely new 5 V supply, from a leftover 5 V power adaptor.

These are the main amplifiers – CD1875 aka LM1875. These are not bad, and can reach -60 to -70 dB distortion, and are generally known as reliable parts.

Some distortions measurement, at two power levels…

… not too bad!

Gain, it’s not quite flat, but OK for the purpose.

Finally, with the new power supply, the Auna has a second life, most likely, even longer than its first.

AB Arboga U2508: adding a “z-axis” digital indicator

The U2508 quill only has a rather coarse indicator, merely, a printed scale (which I had to replace with a new scale, because the old one was completely worn). Still, the quill can be adjusted quite precisely by using the handwheel that will allow a rather precise adjustment, with 2 mm pitch per turn.

The machine has not enough space for a glass scale, and this would be an overkill anyway. Looking around, I found this Wabeco model 11371 digital caliper, 0.01 mm resolution, and usually accurate to within 0.08 mm – most are better than that. The price is quite reasonably, found one set for EUR 38.99, delivered.

For such price, don’t expect too much precision – the mounting holes were quite off-position, and Wabeco confirmed that this is quite common for these units… well, you have to machine the bracket to the caliper’s mounting dimensions, but we aren’t going to produce these brackets in series anyway.

To connect the indicator to the quill rod, a quite sophisticated piece was machined from a scrap piece of high-tensile aluminum alloy.

A few holes drilled and tapped, and – it’s working quite fine.

Another view…

For the mounting of the readout unit, a simple strip of brass was found to be good enough, mounted with two M3 screws to the U2508 – so it can be easily removed, in case the future owner of the U2508, if any, doesn’t like the addition.

Some tests were done, and within 20-30 mm of travel, I could not find any measurable deviation. Don’t have any long gage blocks here but may check it later in case I need super accuracy for some special work.

AB Arboga Maskiner U2508: a simple DRO (linear glass scale readout)

Recently, I have moved a U2508 milling/drilling machine to my Ludwigshafen workshop (from the remote workshop, where there is more space for heavy machinery). It’s a really good machine, slim, but very well built and useful for all kinds of drilling and milling work. It has an automatic feed in in one direction, and the dials are usually quite accurate.

Still, it will be a great advantage of time saving and some accuracy improvement to add a linear scale, at least in the manually-moving direction, so I can mill shoulders and similar features to a very high level of precision and repeatability.

Also the quill will get an electronic readout – but this will be covered later.

Luckily, I had a simple readout around, dating back to 2007, based on an ATmega8515, with some logic, and MAX7219 display drivers.

The case was made from melamine composite boards, these are oil and grease resistant – excellent for workshop use.

Here, the schematic of the input section. The sampling frequency of the counter is about 62.5 kHz, so the TTL signals from the glass scale first pass through a ~160 kHz low pass filter, and are then squared up by Schmitt triggers, 74LS14.

The main processor is running at 16 MHz, and very few extra parts are needed to drive the LED 7-segment displays, using two MAX7219 in chain configuration. The LED segment displays are much preferred for workshop and DRO use, because speed and clarity is everything for this application, and nothing can really replace the good old LED 7-segment displays here.

The power section, note that the regulator will need a heatsink of about 10~15 K/W capacity
– the unit is drawing up to 0.5 Amps at 5 Volts.

The input section…

The drivers…

The wiring, all quickly soldered together with some copper wire.

The code – it uses a gray code approach with continuous sampling of the A/B inputs. This approach is easily coded, and has very deterministic timing, and noise immunity. Any errors found (like, if both lines change state within on sampling cycle) will be indicated by a red LED.

dro_simple1

Now, I only need to mount the glass scale (found one that fits in may parts collection…), and replace the “minus” LED (a 3 mm LED) with a minus bar-shaped LED, just for the better looks.

Note that the software has provisions for a matrix key-pad, but for the present application, the “zero” buttons are all that is needed.

Chuck tender/Bug Filet: Just let it soften in the oven

The chuck tender, also called “bug filet” or “fake filet” in German, is ideally suited for slow cooking. Here my favorite recipe (most just to remember myself, but you may give it a try as well!).

Bug filet marked in red:

Step (1): prepare/wash/dry the meet, about 3-3.5 pounds are ideal.

Step (2): roast all around in hot oil, in a large pot. When almost finished, add about 4 onions, cut into mid-size pieces, and roast further

Step (3): put the meat into a roaster, or other container that is fire-proof and has a lid.

Step (4): add a mixture of about 200 mL of water, 50 mL balsamic vinegar to the onions in the pot, stir thoroughly to remove and dissolve all residue from the pot, and add the liquid to the roaster. You may add some other root vegetables, carrots etc.

Step (5): cover the meat with a mixture of mustard, salt and pepper. Cover.

Step (6): put into the preheated oven, at about 130~140°C. Let cook for about 4 hours. Usually no need to touch, open, etc. – provided the roaster is tightly closed. You can also cook it at 120°C for 5 hours. Under no circumstances use a temperature above 140°C, or any type of short cooking with this meat – it will be tough, and can’t develop the flavor.

Step (7): take the meet from the roaster (check core temperature if you wish, should be about 80°C). Let it rest for 10 minutes. In the meantime, bring the liquids in the roaster to a boil, add some salt, as needed, and add a bit a mixture of starch and water (while boiling and stirring) to give the sauce some texture.

Step (8): cut the meet into rather this slices. Serve with some mashed potatoes.

This dish can be easily stored in the freezer, and re-heated any time. The meet even improves in tenderness and taste.